Some quick pointers I can give:
Basically, creatures can "level up" their stat rarity if played correctly, (there'll be guides and more info in time), thus getting super rare creatures from the opening at level 1 is astronomically difficult on purpose. Basically, the closer you are to average epic rarity the better, if not however, it's not the end of the world, you can still play with them and they'll do well against wild creatures. When it comes to PvP the focus will be that players with a certain rarity face those with a similar rarity to make things even.
Radiant creatures are just aesthetics, it doesn't depend on stats at all, it's a collector thing. However if you can get a creatures average stats to holo rarity, it'll also change its skin. So in a way, the craziest/rarest thing you can get would be a radiant skin and holo stats creature captured in a diamond card. I don't think I need to mention the odds of that. :D
Now when it comes to the empty cards, gold and diamond can capture any type, so u can use those to capture wild creatures in the game if you for instance want a set of all unique creatures in diamond/gold or if you just wanna capture some you think look best in those cards. The other 4 colors stand for creature type so the wild creature will have to be that type to be able to go into those cards. Keep in mind however that alpha cards will be scarce, the ones that get minted from alpha vials will be all that will ever exist. Thus don't waste them on "any" wild creatures if you suspect they have low stats, or save them to attempt to capture radiant wild creatures.
Idiot guides please. :D
I think it is good to have a match-maker system where possible, to stop domination.
This is good to know!